1. Field of the Invention
The invention relates to a molded surface fastener integrally molded from a thermoplastic synthetic resin. More particularly, the invention relates to a molded surface fastener, which is suitable to a case that engaging elements having substantially same shapes are securely engaged with each other by pressure.
2. Description of the Related Art
Conventionally, a molded surface fastener, which is integrally molded on a-plate-like substrate from a synthetic resin material and enables engaging elements having substantially same shapes to be engaged with each other by pressure, has been used, since the engagement operation of the molded surface fastener is easy, the engaging strength of the molded surface fastener is high, so that the molded surface fastener is particularly suitable for engaging an industrial material and an interior decoration or the like.
For example, a molded surface fastener disclosed in Japanese Patent Application Laid-Open No. 2994464 comprises a mushroom engaging element having a rising portion which rises from a surface of a plate-like substrate and decreases a cross sectional area from a base end to an upper end, and an engaging head, which is located on a top end of this rising portion and is expanded around a circumference of this top end in a horizontal direction. In the molded surface fastener having such a shape, the engaging element works together with an engaging element of a mating surface fastener having the same shape at the time of their engagement, so that part of the head deforms elastically and the engaging element is expanded and contracted in a horizontal direction. Consequently, the engaging element is engaged with the engaging element of the mating surface fastener.
Alternatively, for example, a molded surface fastener disclosed in U.S. Pat. No. 5,212,853 is provided with a gate type engaging element comprising a pair of leg portions rising from a surface of a substrate and an engaging head which couples top ends of these leg portions and is expanded in a horizontal direction orthogonal to an arranging direction of these leg portions. According to such a molded surface fastener, upon engaging, part of the head of the engaging element is elastically deformed as working with an engaging element of a mating surface fastener having the same shape to be enlarged and contracted in a horizontal direction, so that the engaging element is engaged with the engaging element of the mating surface fastener. Further, a columnar projection is protruded on a top portion of the engaging head or a position corresponding to the engaging head of the mating surface fastener on a surface of a substrate. The height of the columnar projection is set so that the columnar projection abuts against a surface of the substrate opposing to the each columnar projection or a top portion of an engaging head. Therefore, it is possible to prevent the stagger in a direction orthogonal to an engaging face between the engaged two surface fasteners.
The molded surface fastener disclosed in the Japanese Patent Application Laid-Open No. 2994464 provides a mushroom engaging element having the engaging head, which is located on the top end of the rising portion and is expanded around the circumference of this top end in a horizontal direction. Further, one engaging element is capable of being engaged with a plurality of engaging elements of the mating surface fastener in all directions of the engaging head, so that a high engagement ratio is secured. However, since a neck portion between the rising portion and the engaging head of the engaging element is narrow, the engaging heads are pulled to opposite directions each other upon releasing the engaging elements of an engagement state, so that the neck portions thereof are apt to be broken off. As such releasing operations are repeated, the engagement force is lowered and an original function as a surface fastener has been lost for a short period of time.
Further, the molded surface fastener disclosed in the in U.S. Pat. No. 5,212,853 provides the gate-type engaging element expanded only in opposite horizontal two directions orthogonal to the arranging direction of the leg portions of the rising portion. Therefore, upon releasing the engaging elements, the heads are not broken off as the mushroom engaging element, so that the engagement force between the rising portion and the engaging head is secured. However, the engaging head is engaged with the adjacent two engaging elements only in the expanding opposite two directions but it is not engaged with the mating fastener in the arranging direction of the leg portions. Therefore, if the engaged surface fasteners are displaced each other in the arranging direction of the leg portions of the engaging element, the engagement force is lowered, so that the surface fastener is easily peeled off.
This invention has been made to solve the problem mentioned above, and an object of the invention is to provide a molded surface fastener, which has no stagger between the once engaged engaging elements and has high engagement force so as to strongly prevent the release of the engaging elements.
In order to achieve the object, according to the invention, it is provided a molded surface fastener made of a synthetic resin, in which many engaging elements are integrally molded on a surface of a plate-like substrate and which is capable of being engaged with and disengaged from an engaging element of a mating surface fastener having the same shape thereof. Further, it is a character of the molded surface fastener that the engaging element has a rising portion, which rises from a surface of the plate-like substrate and in which a pair of opposite side faces are defined as inclined faces, an engaging head, which is continuously formed on a top end of the rising portion and which is expanded in a horizontal direction at the other opposite side faces except for the inclined faces, and a fitting projection, which is projected from a surface of the plate-like substrate, is positioned between the facing inclined faces of an adjacent pair of engaging elements of a mating surface fastener upon engaging the engaging elements each other and has an inclined face, which is fit with and abuts against at lease one of both inclined faces.
In such a molded surface fastener, the engaging head of the engaging element is expanded in a horizontal direction only at other side faces except for the inclined face of the rising portion. And an expanded side margin is engaged with a side margin of the engaging head of the engaging element of the mating surface fastener at the expanded side margin of the engaging head. By applying such a shape of the engaging element as having the engaging head expanded only at other side faces, it is possible to secure a sufficient engagement force as same as the molded surface fastener disclosed in U.S. Pat. No. 5,212,853.
Alternatively, the molded surface fastener has a fitting projection, which is located between the facing inclined faces of an adjacent pair of engaging elements of the mating surface fastener upon engaging the engaging elements each other and has inclined faces which fit with and abuts against at lease one of both inclined faces of the engaging elements, so that it is possible to effectively prevent the displacement of the engaged surface fasteners in a horizontal direction and the engagement state is certainly maintained. Meanwhile, according to the invention, the fitting and abutting means a case such that the inclined face of the engaging element and the inclined face of the fitting projection are contacted each other and a case such that these inclined faces abut each other with a narrow gap.
Further, according to the molded surface fastener, it is preferable that the fitting projection is located in a position so as to be fit with and abut against both for facing inclined faces of an adjacent pair of engaging elements of the mating surface fastener. Thus, if the fitting projection is fit with and abuts against the both of facing inclined faces of an adjacent pair of engaging elements of the other surface fastener, the displacement between the engaged surface fasteners in a horizontal direction is perfectly prevented.
Further, a pair of the opposite inclined faces of one engaging element are inclined so as to come close each other gradually from a base end to a front end. Thus, if a cross sectional area of the rising portion is progressively increased from the front end to the base end as a joint portion with a surface of a substrate, the strength of the rising portion is increased. Additionally, even in the case that a side face of the engaging head at the expanding side is formed in vertical with respect to a surface of the substrate, because of the existence of the adjacent fitting projection, the surface fasteners are supported by the fitting projection even if they are bent to the vertical face upon pressing the fasteners, so that bending and falling down of the rising portion is restrained and it is possible to secure a required engagement ratio.
Alternatively, a pair of the opposite inclined faces of one engaging element are inclined so as to be substantially in parallel with each other from a base end to a front end. In such an engaging element, particularly, it is preferable that adjacent two engaging elements are shaped in a substantially V with the base ends of their rising portions jointed.
Thus, if the adjacent two engaging elements are jointed at their base ends of the rising portions and part of the rising portion is shared, it is possible to increase the strength of the rising portion. Alternatively, the adjacent two engaging elements are shaped in a substantially V and the engaging heads thereof are bent to the opposite direction so as to be apart each other by the pressure of the surface fasteners upon their engagement, so that it becomes easy to insert the fitting projection between the both engaging elements.
Meanwhile, it is preferable that a shape of the fitting projection is substantially identical with a shape of a space defined between the facing inclined faces of the adjacent pair of engaging elements of the mating surface fastener. For example, it is considered that the fitting projection has a cross section entirely shaped in a substantially trapezoid, or the fitting projection has a cross section entirely shaped in a substantially triangle.
Further, the integrally molded surface fastener has a constitution such that the fitting projection elastically contacts the engaging element firmly. Thus, by elastically contacting the fitting projection and the inclined face of the engaging element, the fitting projection is strongly fit between the engage elements, so that it becomes possible to more effectively prevent the displacement between the engaged two surface fasteners.
As a constitution in order to elastically contact the fitting projection and the inclined face of the engaging element, for example, a constitution such that the fitting projection or the engaging element is manufactured in a hollow shape and in a gate shape and a constitution such that the fitting projection is formed with a pair of elastic projections disposed at a specific distance in the arranging direction of the inclined face are considered.
Further, the projection height of the fitting projection is not more than the height of the engaging element. If the height of a projection in the fitting projection is higher than the height of the engaging element, a gap is generated between a top portion of the engaging element and a surface of the substrate of the mating surface fastener. This state is not desirable. In this case, in order to prevent the stagger in a direction orthogonal to an engagement face, it is further preferable that the height of the projection in the fitting projection is the same as the height of the engaging element.
Furthermore, the fitting projection is formed in the middle of the adjacent two engaging elements. For example, in the case that the inclined faces of the engaging element are arranged in a molding direction, the fitting projection is formed in the middle of the two engaging elements adjacent in a width direction of the resurface fastener. In this case, one engaging element is located between four engaging elements of the mating surface fastener, which are adjacent in a back/forth direction and a right/left direction, and engaged with the four engaging elements.
Alternatively, the fitting projection is formed in the middle of four engaging elements adjacent in a back/forth direction and a right/left direction. In this case, one engaging element is located between two engaging elements adjacent in a width direction of the mating surface fastener and is engaged with an expanded side margins of two engaging elements of the mating surface fastener at the expanded two side margins of the engaging head of this engaging element.